Compliantly mountable turbine cartridge assembly for gas-driven dental handpiece

ABSTRACT

A single-unit turbine cartridge assembly for a gas-driven dental handpiece includes a pair of bearing assemblies mounted on a turbine rotor shaft and a ring of resilient material around each bearing assembly. The resilient ring provides radial support for the turbine cartridge assembly within the housing of the handpiece and substantially dampens the transfer of vibration from the cartridge assembly to the handpiece during use of the handpiece. The turbine cartridge assembly may optionally include bearing axial pre-load means in association with one or more of the bearing assemblies. The turbine cartridge assembly also includes means for retaining the resilient radial support means and the bearing axial preload means, when used, in association with the bearing assemblies, so as to permit removal, and reinstallation, of the cartridge assembly as an entire unit from, and to, the housing in the dental handpiece.

BACKGROUND OF THE INVENTION

1. Field

Dental handpieces having gas-driven motors are well known. Of particularinterest herein is a high-speed gas-driven dental handpiece havingdecreased noise and improved vibration damping characteristics.

2. State of the Art

A dental handpiece of a type having a high-speed gas-driven motor, ofwhich the turbine rotor and bearings are replaceable as a multi-pieceunit within the motor housing, is described in U.S. Pat. No. 3,074,167to Turchi et al. A rotor of a high-speed motor of this type will rotateat speeds of 250,000 to 400,000 rpm, or more, during use of thehandpiece by a dentist. Significant amounts of vibration and noise maybe transmitted from the motor to the handle portion during use of ahigh-speed handpiece having a rotor bearing cage in direct contact withthe handpiece motor housing, such as shown in the Turchi et al U.S. Pat.No. 3,074,167 patent. Vibration and noise even in small amounts can bequite disturbing to dentist and patient alike, and may be especiallydisturbing when, at certain critical rotor operating speeds, resonanceeffects greatly enhance or amplify the noise or vibration originatingfrom the gas-driven motor.

A high-speed handpiece having reduced vibration and noise transmittingcharacteristics is disclosed in U.S. Pat. No. 3,499,223 to Lieb et al,wherein vibration damping rings fabricated of non-metallic or rubberymaterials are interposed between the metallic rotor bearings and ametallic motor housing. These vibration damping rings are described asinsertable within a gas-driven motor housing separately from the turbinerotor-and-bearing assembly. A disadvantage of this arrangement is thatduring removal and reinstallation of a turbine assembly by a handpieceuser in a dental office one or both of the vibration damping rings mayfrequently become lodged in the motor housing, with resultant difficultyfollowing in the removal of the ring. Also, reinstallation of each ringseparately from the turbine-and-bearing assembly is a time-consumingchore requiring a relatively high degree of care to avoid improperorientation or seating of the ring in the motor housing.

Another problem associated with proper installation or positioning of aturbine-and-bearing assembly within a gas-driven motor housing is inobtaining proper rotor alignment and static pre-loading of the bearingswithin the housing. One aspect of proper rotor alignment is the degreeof concentricity maintained between the motor housing axis and the axisof rotation of a dental bur which is mounted by its shank within theturbine cartridge assembly rotor shaft. The degree of concentricity is,in turn, related to bur run-out, that is, the distance of movement of arotating bur from its theoretical axis as measured in a planeperpendicular to the rotor shaft axis, the plane intersecting the tip ofthe bur. Typically, a dental bur has some imbalance as a result ofmanufacture or because of an irregular configuration of the bur worksurface. The combination of poor concentricity and bur imbalance mayprovide a considerable amount of vibration during use of the handpieceespecially at or near the critical frequency of rotation of the turbine.

Improper axial or radial alignment of the rotor shaft with respect tothe motor housing, or the application of too little or too much staticpre-loading to the rotor shaft bearings, may also lead to excessivenoise and vibration causing pre-mature wear and failure of the bearings.The problem of misalignment may be especially acute with a handpiecehaving separately-installed vibration damping rings, or spring-likebearing pre-loading elements, or both, where special care must be takento prevent distortion of the rings, misalignment of the rotor, improperstatic pre-loading of the bearings, or loss of the variousseparately-installed components.

There is need, therefore, for a high-speed gas-driven dental handpiecehaving a turbine-and-bearing assembly which can be easily removed andreinstalled in a motor housing as a unitary assembly which contains allof the various parts for achieving proper radial and axial alignment toprovide a high degree of concentricity, and which turbine cartridgeassembly when installed in a handpiece motor housing may provide aproper degree of static preloading to the rotor shaft bearings.

SUMMARY OF THE INVENTION

A turbine-and-bearing assembly for a high speed gas-driven motor of adental handpiece of the present invention provides an advantage ofimproved ease of removal and reinstallation of the turbine assembly froma motor housing as a unitary assembly. Secondly, the turbine assembly ofthis invention is easily alignable within a motor housing in a mannerthat provides a proper degree of pre-loading force to the rotor shaftbearings for minimum wear of the bearings. The turbine assembly of thisinvention when installed in a high-speed dental handpiece provides lowtransmission of vibration from the motor housing to the handle portionof the handpiece and reduced bur run-out.

These and other advantages are provided by a turbine cartridge assemblywhich is removably positionable as a unit within a housing of agas-driven motor of a dental handpiece. The motor housing is typicallylocated in one end portion of a dental handpiece and is defined by asubstantially cylindrical side wall and a pair of oppositely disposedend walls transverse to the side wall, with means for supporting aturbine cartridge assembly located on portions of the side wall and endwalls. The turbine cartridge assembly may in one embodiment comprise arotor shaft having a plurality of vanes thereon, the rotor shaft havingan axis of rotation substantially coincident with the axis of thecylindrical side wall of the motor housing, a first bearing assemblycomprising an inner race fixed to the rotor shaft, an outer race, and aplurality of movable bearing elements frictionally engaged with andconfined between the inner race and the outer race, a second bearingassembly comprising an inner race fixed to the rotor shaft in spacedrelationship with the inner race of the first bearing assembly, an outerrace, and a plurality of movable bearing elements frictionally engagedwith and confined between the inner race and the outer race of thesecond bearing assembly, radial support means associated with each ofthe first and second bearing assemblies, the radial support meansproviding radial support for the turbine cartridge assembly when incontact with the substantially cylindrical side wall of the motorhousing, rigid axial support means associated with the outer race of thefirst bearing assembly for axially supporting the first bearing assemblyouter race upon turbine cartridge support means located on an end wallportion of the housing, bearing pre-loading means comprising flexibleaxial support means associated with the outer race of the second bearingassembly for yieldingly supporting the outer race upon turbine cartridgesupport means located on an end wall portion of the housing to provide acontrolled axial force on the outer race of the second bearing assembly,which force is transmitted through the rotor shaft to the first bearingassembly to provide pre-loading to the first bearing assembly, and meansfor retaining the radial support means and the flexible axial supportmeans upon the outer race of the second bearing assembly. The rigidaxial support means and the flexible axial support means coact with theturbine cartridge support means on the housing end wall to provide axialpre-loading of the first and second bearing assemblies when the turbinecartridge assembly is operatively positioned within the motor housing.

The aforementioned rigid axial support means and flexible axial supportmeans comprise means for yieldingly coacting with the turbine cartridgeassembly support means in the motor housing of a dental handpiece toprovide axial pre-loading of the first and second bearing assemblieswhen the turbine cartridge assembly is operably positioned within themotor housing. It is an advantage of the invention that various degreesof preloading may be provided for a turbine cartridge assembly by theaxial pre-load means to compensate for varying degrees of tolerancesthat exist between components of one bearing assembly and another. Thusbearing assemblies may be employed which have a broader range ofcomponent tolerances or "stop" between bearing components therebyproviding an advantage in economy of manufacture.

It is another feature of the invention that the entire turbine cartridgeassembly is adapted for placement in, and removal from, the housing as aunitary assembly so that during field replacement of the turbinecartridge assembly, the various means for obtaining proper rotoralignment, bearing pre-load or vibration damping are retained on theturbine cartridge assembly and need not be separately removed from, orinserted in, the handpiece motor housing.

The rigid axial support means typically comprises a flange extendingradially outwardly from and integrally formed with the outer race ofeach of the first and second bearing assemblies, although various otherconstructions affording a rigid flange, or the equivalent thereof, maybe provided. The flexible axial support means typically includes atleast one resilient spacer member circumferentially disposed about atleast one of the bearing assembly outer races. The resilient spacermember, interposed between the turbine cartridge support means locatedon the motor housing end walls and the rigid axial support means of theouter race of one of the bearing assemblies, is adapted to transmit acontrolled compression force therebetween so as to urge the outer racetoward the rotor vanes in a direction substantially parallel with theaxis of the rotor shaft. It is preferred that the resilient spacermember have a spring constant sufficient to provide a static pre-load toeach of the bearing assemblies in the axial direction in the range ofabout 0.5 to about 1.5 pounds when the turbine cartridge assembly isoperably positioned within the motor housing.

The turbine cartridge assembly also includes means for retaining theflexible axial support means and other support components upon the outerrace of the second bearing assembly and may also include means forretaining the rigid axial support means and other support componentsupon the outer race of the first bearing assembly, particularly wherethe rigid axial support means is not integrally formed with the outerrace. Retention of these various support means upon each of the bearingassembly outer races allows removal and reinstallation of all componentsof the turbine assembly as a unitary cartridge, which thus precludes theloss of the support components during handling of the turbine cartridgeassembly.

The turbine cartridge assembly includes radial support means whichprovide radial support for each of the first and second bearingassemblies against the substantially cylindrical side wall of thehousing. In addition to providing proper radial positioning of theturbine cartridge assembly with respect to the motor housing side wall,it is desirable that the radial support means ideally have mechanicalproperties which inhibit the transmission of vibration from a rotatingturbine cartridge assembly to the motor housing. In preferredembodiments of the invention, the radial support means comprises a ringof resilient material interposed between each of the first and secondbearing assembly outer walls and a portion of the housing cylindricalside wall adjacent each of the bearing assemblies. These resilient ringsare characterized in providing sufficiently rigid radial support of theturbine cartridge assembly while, at the same time, providing means fordamping or reducing the transmission of vibration between the turbinebearings and the motor housing.

A dental handpiece having a turbine cartridge assembly of this inventionwhich includes radial support means comprising resilient,vibration-damping rings may be described as compliantly mounted orsuspended within the handpiece motor housing.

A significant advantage is provided by a turbine cartridge assembly ofthis invention including radial support means comprising resilientmembers having a particular physical characteristic, as hereinafterdefined. In some conventional handpieces having metallic orsubstantially non-resilient supports between the turbine bearings andthe motor housing, there may be a very low degree of resilience, asmeasured by spring rate, of about 5000 pounds per inch. This very highspring rate provides for little damping of vibration between the bearingand the motor housing. In the present invention, resilient elements areutilized between the turbine cartridge bearing assemblies and the motorhousing wall, which resilient elements have spring rates of 80 to 100pounds per inch. This greatly reduced spring rate provides improveddamping of vibration which is characteristic of the compliantlymountable turbine cartridge assembly of this invention.

The radial support means of the turbine cartridge assembly of theinvention may, however, in a lesser preferred embodiment, comprisesubstantially non-resilient members such as provided by the metallicouter wall of each of the bearing assembly outer races.

In another embodiment of the invention, the turbine cartridge assemblymay comprise a rotor shaft having a plurality of vanes thereon, therotor shaft defining an axis of rotation, a first bearing assemblycomprising an inner race fixed to the rotor shaft, an outer race, and aplurality of movable bearing elements frictionally engaged with theconfined between the inner race and the outer race, a second bearingassembly comprising an inner race fixed to the rotor shaft, an outerrace, and a plurality of movable bearing elements frictionally engagedwith and confined between the inner race and the outer race of thesecond bearing assembly, radial support means associated with each ofthe first and second bearing assemblies, the radial support meanscomprising a resilient member interposed between each of the bearingassemblies and an adjacent portion of the housing side wall, the radialsupport means providing vibration-damping radial support for the turbinecartridge assembly upon the substantially cylindrical side wall of ahandpiece housing, and retaining means mounted on each of the bearingassembly outer races for retaining the radial support means upon theturbine cartridge assembly. Though this embodiment lacks flexiblesupport means or the aforementioned means for yieldingly coacting withthe turbine cartridge assembly support means, which provide axial staticpre-loading of the bearing assemblies, the inclusion of radial supportmeans having a resilient, vibration-damping nature provides acompliantly mountable or suspendable turbine cartridge assembly for ahandpiece housing. Inasmuch as there is a lack of the aforementionedaxial pre-load means, the turbine cartridge assembly may require bearingassemblies having component tolerances which provide a limited amount ofbearing axial end play to ensure low vibration or noise levels.

DESCRIPTION OF PREFERRED EMBODIMENTS

The means providing the features and advantages of the present inventionare illustrated in the accompanying drawings wherein:

FIG. 1 is a perspective view of a dental handpiece illustrating therelative locations of a high-speed gas-driven motor housing and ahand-grippable portion;

FIG. 2 is a side elevational view, partly in section, showing theposition of the presently preferred turbine cartridge assembly of thepresent invention within the handpiece motor housing of FIG. 1;

FIG. 3 is a side elevational view, partly in section, of the turbinecartridge assembly of FIG. 2;

FIG. 4 is a side sectional view of a second embodiment of a turbinecartridge assembly of this invention;

FIG. 5 is a side sectional view of a third embodiment of a turbinecartridge assembly of this invention;

FIG. 6 is a side sectional view of a fourth embodiment of a turbinecartridge assembly of this invention; and

FIG. 7 is a side sectional view of a fifth embodiment of a turbinecartridge assembly of this invention.

Illustrated in FIG. 1 is a dental handpiece 10 including a barrel-shapedhandle portion 11 having an outer wall 12 with flutes 13 which provide ahand-grippable surface. Handle portion 11 has at one end thereof anelongated neck 14 joined to handle portion 11 at a knuckle 15. Neck 14terminates in head 16 having a gas-driven motor 17 provided by a motorhousing 18 and turbine cartridge assembly 19, as depicted in FIG. 2.Motor housing 18 is defined by a substantially cylindrical inner sidewall 20, having an axis lying generally transverse to the axis of neck14, and by a pair of oppositely disposed end walls transverse to sidewalls 20. One housing end wall 21 is integrally formed with housing sidewall 20 within head 16. The other housing end wall is furnished by endcap 22 which has an annular-shaped flange 23 extending into housing 18in a generally axial direction. Flange 23 has an exteriorly threadedportion 24 which engages an interiorly threaded portion 25 on anadjacent portion of side wall 20. End cap 22 contains an orifice 26which, when end cap 22 is threadedly secured to housing side wall 20, isaxially aligned with an orifice 27 in oppositely disposed end wall 21.

Integrally formed along a portion of housing side wall 20 near end wall21 is an annular-shaped ledge or shoulder 28 which extends radiallyinwardly toward the axis of housing 18. Shoulder 28 comprises a part ofend wall 21 and provides a portion of the means for supporting turbinecartridge assembly 19 within housing 18. At the opposite end of housing18, annular flange 23 of end cap 22 provides an annular-shaped shoulder29 which also comprises a portion of the means for supporting turbinecartridge assembly 19 within housing 18.

Turbine cartridge assembly 19 comprises an elongated rotor shaft 30having an axis of rotation that is substantially coincident with theaxis of motor housing 18. Rotor shaft 30 has an axial bore 31 extendingthe length thereof. There is an interiorly threaded portion 32 at theend of rotor shaft 30 adjacent end cap 22. At its opposite end, rotorshaft 30 has a tapered portion 33 which slopes inwardly toward the axisof rotor shaft 30. Contained within rotor shaft bore 31 is a collet 34having at one end an exteriorly threaded portion 35 which engagesthreaded portion 32 of rotor shaft 30. At its opposite end, collet 34has a plurality of jaws 36 for gripping a shank 37 of a work tool whencollet 34 is threaded into rotor shaft 30. Additional details andadvantages of construction of a dental handpiece having the illustratedcollet may be found in U.S. Pat. No. 3,120,706 to Turchi et al, thedisclosure of which is incorporated herein by reference. A descriptionof means for inserting and removing a work tool, such as a dental bur,into and from collet 34 may be found in U.S. Pat. No. 3,947,966 to Liebat al.

Rotor shaft 30 is journalled upon a pair of first and second bearingassemblies 38 and 39, respectively, which are in axially spacedrelationship along rotor shaft 30. It should be noted that the terms"first" and "second" designating bearing assemblies 38 and 39 are forconvenience of discussion only, and that either bearing assembly couldbe designated "first" or "second" since the designation is entirelyarbitrary. Hence, the following description relating to the "firstbearing assembly" may, as well, relate to the "second bearing assembly",and vice versa.

First bearing assembly 38 comprises a ring-like inner race 40, which isfixedly journalled upon a portion of rotor shaft 30 adjacent end cap 22,and a ring-like outer race 41 spaced therefrom. Inner race 40 and outerrace 41 provide a bearing housing in which a plurality of movable ballbearing elements 42 can be confined between and frictionally engagedwith races 40 and 41. Second bearing assembly 39 similarly comprises aninner race 43, an outer race 44 and movable ball bearing elements 45confined and frictionally engaged therebetween. Inner race 43 is fixedlyjournalled upon rotor shaft 30 in spaced relationship with inner race 40of first bearing assembly 38, that is, inner race 43 of second bearingassembly 39 is journalled upon a portion of rotor shaft 30 closer to endwall 21. Alternatively, inner races 40 and 43 could as well beintegrally formed with rotor shaft 30.

Rotor 46 including a plurality of vanes 47 radiating outwardly fromrotor shaft 30 is fixedly journalled upon rotor shaft 30 between firstand second bearing assemblies 38 and 39. Vanes 47 impart rotationalmovement to rotor shaft 30 when a high velocity gas stream impinges uponvanes 47, as is well known in the art. A suitable high velocity gasstream may be provided from an external source of compressed air (notshown) connected to passageway 48 within handle portion 11, whichpassageway 48 is in communication with motor housing 18 by means ofinlet port 49 in motor housing side wall 20. An exhaust port 50 inanother portion of side wall 20 spaced from inlet port 49 providescommunication between motor housing 18 and exhaust passageway 51.Exhaust air flows from the motor housing via port 50 and the hollowportions of handpiece 10 within neck 14 and handle portion 11 during useof the handpiece.

Outer races 41 and 44 of first and second bearing assemblies 38 and 39,respectively, each have substantially cylindrically shaped outer walls52 and 53 facing in a direction radially outwardly of the axis of rotorshaft 30. When turbine cartridge assembly 19 is positioned within motorhousing 18, the face of each of convex outer walls 52 and 53 issubstantially concentric with the portions of cylindrically-shapedconcave housing side wall 20 adjacent thereto. Outer wall 52 of firstbearing assembly outer race 41 has a flange 54 integrally formed as theedge portion thereof closer to second bearing assembly 39. Flange 54extends radially outwardly from the face of outer wall 52 with respectto the axis of rotor shaft 30. Preferably, flange 54 extendscircumferentially about outer wall 52 to provide an annular ledge orshoulder 55. Similarly, outer wall 53 of second bearing assembly outerrace 44 has a flange 56 integrally formed as the edge portion thereofcloser to first bearing assembly 38. Flange 56 extends radiallyoutwardly from the face of outer wall 53 with respect to the axis ofrotor shaft 30. Flange 56 preferably extends circumferentially aboutouter wall 53 to provide an annular ledge or shoulder 57.

Adjacent flange shoulder 55 of first bearing assembly 38 is a flatwasher 58 having an annular or ring-like shape, which washer 58 liescircumferentially about outer wall 52. The inner diameter of washer 58is less than the outer diameter of flange shoulder 55, as measured in aplane substantially perpendicular to the axis of rotor shaft 30, whilethe outer diameter of washer 58 is greater than the outer diameter offlange shoulder 55. A ring-like flat washer 59 of construction similarto washer 58 lies circumferentially about outer wall 53 near flangeshoulder 57 of second bearing assembly 39.

Flat washers 58 and 59 provide rigid support means for supportingturbine cartridge assembly 19 upon annular-shaped shoulders 29 and 28,respectively, located on end cap 22 and side wall 20 of motor housing18, when turbine cartridge assembly 19 is operably positioned withinhousing 18. Each of flat washers 58 and 59 tends to prevent movement ofouter races 41 and 44, respectively, in opposite directions away fromrotor vanes 47 along the axis of rotor shaft 30.

The rigid axial support means may be provided by other constructions inaddition to those described above. For example, as shown in FIG. 6,grooves 80 and 81 each run circumferentially about outer walls 52 and53, respectively, with each of the grooves lying in a planesubstantially perpendicular to the axis of rotor shaft 30. Within eachof grooves 80 and 81 is a snap ring 82 and 83, respectively, retainedwithin the grooves, and in rigid connection with the respective outerraces, by the spring bias of the snap ring. Snap rings 82 and 83 provideshoulders 84 and 85, respectively, extending radially outwardly of outerrace outer walls 52 and 53, respectively. Shoulders 84 and 85 each havean outer diameter in the radial direction sufficient to provide rigidaxial support for the turbine cartridge assembly upon annular shoulders29 and 28, respectively.

Another variation of the rigid axial support means is depicted in FIG.7. Integrally formed with bearing assembly outer race 41 is a flange 86which has an outer diameter in the radial direction sufficient to definea shoulder 87 which provides axial support for turbine cartridgeassembly 19 upon end wall shoulder 29 of motor housing 18. Flange 86thus provides rigid axial support like the combination of flange 55 andflat washer 58 depicted in FIG. 3, for example.

As depicted in FIG. 2, there is provided in association with secondbearing assembly 39 a resilient spacer member comprising a wavey springwasher 60 interposed between flange shoulder 57 and flat washer 59.Spring washer 60 has a substantially sinuous configuration and thusprovides a spring-like thrust tending to urge outer race 44 toward outerrace 41 in an axial direction. With turbine cartridge assembly 19operably positioned within housing 18, flat washer 59 of second bearingassembly 39 is supported by shoulder 28 located on a portion of housingside wall 20. A reaction force from shoulder 28 through flat washer 59opposes the spring compression force of spring washer 60.

Likewise, other embodiments of the turbine cartridge assembly of theinvention may have a spring washer 60 associated with second bearingassembly 39. As shown in FIG. 5 spring washer 60 is interposed betweenshoulder 85 of snap ring 83 and flat washer 59. In the turbine cartridgeassembly of FIG. 7, spring washer 60 may be interposed between flangeshoulder 57 and end wall shoulder 28 when the turbine cartridge assemblyis operably positioned within motor housing 18. In each of theseconstructions, a reaction force is transmitted between a portion ofhousing end wall 21 and second bearing assembly outer race 44.

Total axial loading of first and second bearing assemblies 38 and 39 maybe accomplished with a single wavey washer 60 positioned in associationwith second bearing assembly 39 as depicted in FIGS. 2, 5 and 7. Theillustration of transmitted forces within turbine cartridge assembly 19,as indicated by the arrows in FIG. 2, demonstrates the manner in whichaxial preloading of both bearing assemblies of turbine cartridgeassembly 19 may be accomplished by a single spring washer 60. Thepre-load compression force exerted by wavey washer 60 is transmittedthrough outer race 44 of second bearing assembly 39 to ball bearingelement 45 then to inner race 43 affixed to one end of rotor shaft 30.At the other end of rigid rotor shaft 30, the pre-load force istransmitted from the rotor shaft through inner race 40 of the firstbearing assembly to ball bearing element 42 and then to outer race 41which is restrained from axial displacement away from rotor vanes 47 byflat washer 58 supported upon annular shoulder 29 of end cap 22. Axialpre-loading is likewise achieved by a single spring washer 60 in theturbine cartridge assemblies of FIGS. 5 and 7.

In another embodiment of the turbine cartridge assembly as depicted inFIG. 4, resilient spacer members comprising wavey spring washers 61 and60, respectively, are associated with each of first and second bearingassemblies 38 and 39. Each of wavey washers 60 and 61 has a sinuousconfiguration and provides a spring-like thrust tending to urge outerraces 41 and 44 toward each other in the axial direction. The two springwashers 60 and 61 thus cooperate to provide a total pre-loading of thefirst and second bearing assemblies.

Typically, a suitable spring washer is fabricated of materials such asspring steel or phosphor bronze and will have dimensions and a springconstant adapted to the particular configuration and desired degree ofaxial play of the bearing assemblies of a turbine cartridge assembly. Itis preferred that in either embodiment illustrated in FIG. 2 and FIG. 3the total axial pre-loading of the first and second bearing assemblies,as provided by one or more wavey washers, should be in the range ofabout 0.5 to about 1.5 pounds, which provides a good balance between lownoise and vibration characteristics and long bearing life.

Although the described axial pre-loading means may be used successfullyin a turbine cartridge assembly designed to have bearing assemblieswhich are in direct frictional contact with a motor housing side or endwalls, it is preferred that resilient spacer rings be interposed betweenthe bearing assemblies and adjacent portions of housing side wall 20 toprovide radial support and a compliant mounting or suspension forturbine cartridge assembly 19. As illustrated in FIG. 2, a pair ofresilient rings 62 and 63, such as commercially available O-ringsfabricated of rubbery material, lie circumferentially about outer walls52 and 53 of the outer races of first and second bearing assemblies 38and 39, respectively. Preferably, each of O-rings 62 and 63 has an innerdiameter in the radial direction with respect to the axis of rotor shaft30 which is slightly less than the outer diameter of outer walls 52 and53 so that each of O-rings 62 and 63 is in a slightly stretchedconfiguration around its respective outer race. Each of resilientO-rings 62 and 63 will have an outer diameter slightly greater than thediameter of the housing at the portion of the housing side wall adjacentto the O-ring. Thus when turbine cartridge assembly 19 is positionedwithin housing 18, O-rings 62 and 63 become compressed in the radialdirection. This radial compression of the O-rings provides both a sleeveor frictional fit and suitable alignment of turbine cartridge assembly19 within housing 18. In addition to inhibiting radial displacement ofthe turbine cartridge assembly, the O-rings inhibit transfer ofvibration from the cartridge assembly to the handle portion during useof the handpiece.

The O-rings 62 and 63 may be fabricated of practically any elastic orresilient material that has good vibration and noise damping propertiesand which resists high temperature and steam conditions typical ofrepeated autoclave cycles required for sterilization during the usefullife of the dental instrument. Satisfactory materials include, forexample, neoprene elastomer, ethylenepropylene elastomer, fluorocarbonelastomer and butadiene/acrylonitrile elastomer (known commercially asBuna-N rubber).

A significant advantage of a turbine cartridge assembly of thisinvention is provided by the ease of removal and replaceability of theturbine cartridge assembly from and to a dental handpiece, which isattributable to the feature of all of the components of the turbinecartridge assembly being removed or replaced as a unitary assembly. Theaforementioned one or more spring washers for effecting proper bearingpre-loading and the resilient O-rings which provide vibration and noisedamping are all retained on the turbine cartridge assembly, therebyprecluding removal or reinsertion of these parts separately from otherturbine components.

Retention of the spring washers or the O-rings on the turbine cartridgeassembly may be accomplished by cooperation of bearing outer raceflanges 54 and 56 with various means associated with the outer race ofeach bearing assembly. For example, in some constructions each ofO-rings 62 and 63 may have a sufficiently secure friction fitting withthe respective outer wall of first and second bearing assembly outerraces 41 and 44 to prevent axial movement of one or more spring washerstoward the ends of rotor shaft 30. More likely, each of first and secondbearing assemblies 38 and 39 will have additional retaining means forkeeping both the one or more spring washers and the O-rings on turbinecartridge assembly 19 as shown, for example, in each of the embodimentsof FIGS. 2, 3 and 4. The retaining means comprise snap rings 64 and 65which rest in grooves 66 and 67 running circumferentially about outerwalls 52 and 53 of first and second bearing assembly outer races 41 and44, respectively. Snap rings 64 and 65 retain flat washers 58 and 59,spring washer 60 (and 61 of the embodiment of FIG. 4) and O-rings 62 and63 upon their respective bearing assemblies, so that none of thesecomponents become lost or misaligned during removal or replacement ofthe turbine cartridge assembly from the motor housing.

As another aspect of the invention, a turbine cartridge assembly maylack the aforementioned bearing axial pre-load means as provided, forexample, by one or more spring washers interposed between one or more ofthe bearing assemblies and adjacent portions of the housing end walls.For example, as shown in FIG. 6, each of first and second bearingassemblies 38 and 39, respectively, has rigid axial support means whichprovide support for turbine cartridge assembly 19 upon end wallshoulders 29 and 28, respectively, when turbine cartridge assembly 19 isoperably positioned within motor housing 18. The rigid support means isdepicted as comprising snap rings 82 and 83 rigidly connected to bearingassembly outer races 41 and 43 by the spring tension of each of snaprings 82 and 83, respectively, within each of grooves 80 and 81. Itshould be understood, however, that any of the other described rigidaxial support means of FIGS. 2, 3, 4, 5 and 7, or combinations thereof,could be utilized as well. Turbine cartridge assembly 19 of FIG. 6 ischaracterized as compliantly mountable, though lacking axial pre-loadingmeans, inasmuch as there is provided radial support means which compriseresilient O-rings 62 and 63.

Each of bearing assemblies 38 and 39 may also contain shield rings 68and 69 resting in grooves 70 and 71, respectively, runningcircumferentially about inner walls 72 and 73 of first and secondbearing assembly outer races 41 and 44, respectively. The purpose ofshield rings 68 and 69 is to aid in retention of lubricant within andaround each of ball bearing retainers 74 and 75 and to retardcontamination of the bearings by entry of particulate matter into thebearing cages.

While this invention has been described with reference to specificembodiments thereof, it should be understood by those skilled in thisart that various changes may be made and equivalents may be substitutedwithout departing from the true spirit and scope of the invention. Allsuch modifications are intended to be within the scope of the claimsappended hereto.

What is claimed is:
 1. A dental handpiece comprising a gas-driven motor,said motor including a housing and a turbine cartridge assembly withinsaid housing, said housing defined by a substantially cylindrical sidewall and by a pair of oppositely disposed end walls transverse to saidside wall, said housing having turbine cartridge assembly support meanslocated on portions of said walls for supporting said turbine cartridgeassembly, said turbine cartridge assembly removably positionable as aunitary assembly within said housing, said turbine cartridge assemblycomprising:a rotor shaft having a plurality of vanes thereon, said rotorshaft having an axis of rotation substantially coincident with the axisof said substantially cylindrical side wall of said housing; a firstbearing assembly comprising an inner race fixed to said rotor shaft, anouter race, and a plurality of movable bearing elements frictionallyengaged with and confined between said inner race and said outer race; asecond bearing assembly comprising an inner race fixed to said rotorshaft, an outer race, and a plurality of movable bearing elementsfrictionally engaged with and confined between said inner race and saidouter race of said second bearing assembly; radial support meansassociated with each of said first and second bearing assemblies, saidradial support means providing radial support for said turbine cartridgeassembly upon said substantially cylindrical side wall of said housing;rigid axial support means connected to said outer race of said firstbearing assembly for axially supporting said first bearing assemblyouter race upon said turbine cartridge support means of said housing;bearing pre-load means comprising flexible axial support meansassociated with said outer race of said second bearing assembly foryieldingly supporting said outer race upon said turbine cartridgesupport means of said housing; first retaining means for retaining saidradial support means upon said outer race of said first bearingassembly, said first retaining means preventing movement of said radialsupport means in an axial direction away from said rotor shaft vanes;and second retaining means for retaining said radial support means andsaid flexible axial support means upon said outer race of said secondbearing assembly, said second retaining means preventing movement ofsaid radial support means and said flexible support means in an axialdirection away from said rotor shaft vanes; whereby said rigid axialsupport means and said flexible axial support means coact with turbinecartridge support means of said housing to provide axial pre-loading ofsaid first and second bearing assemblies when said turbine cartridgeassembly is operatively positioned within said housing.
 2. The dentalhandpiece of claim 1 wherein said radial support means comprisesan outerwall on each of said bearing assembly outer races, said outer wallfacing radially outwardly of the axis of said rotor shaft; and a ring ofresilient material frictionally engaged about a circumferential portionof said outer race outer wall of each of said bearing assemblies, saidring having an outer diameter sufficient to provide a compression fitbetween said outer race outer wall and a portion of said housing sidewall when said turbine cartridge assembly is operably positioned withinsaid housing.
 3. The dental handpiece of claim 2 wherein said ring ofresilient material is an O-ring fabricated of a material selected fromthe group consisting of neoprene elastomer, fluorocarbon elastomer,ethylene propylene elastomer and butadiene/acrylonitrile elastomer. 4.The dental handpiece of claim 1 wherein said rigid axial support meanscomprises a flange connected to said outer race of said first bearingassembly, said flange having an outer diameter in the radial directionsufficient to provide axial support for said turbine cartridge assemblyupon a portion of said housing end wall adjacent said first bearingassembly.
 5. The dental handpiece of claim 1 wherein said rigid axialsupport means comprises:a flange connected to said outer race of saidfirst bearing assembly, said flange extending radially outwardly fromsaid outer race; and a substantially flat washer interposed between saidflange on said first bearing assembly outer race and said turbinecartridge support means of said housing, said flat washer having aninner diameter smaller than the outer diameter of said radiallyextending flange, and having an outer diameter of sufficient dimensionso that said flat washer supports said outer race upon turbine cartridgeassembly support means located on an end wall portion of said housingadjacent said first bearing assembly.
 6. The dental handpiece of claim 1wherein said rigid axial support means comprisesan outer wall on saidfirst bearing assembly outer race, said outer wall facing radiallyoutwardly of the axis of said rotor shaft; a groove runningcircumferentially about said outer race outer wall, said groove lying ina plane substantially perpendicular to the axis of said rotor shaft; aspring-like snap ring retained within said groove, said snap ringforming a shoulder extending radially outwardly of said outer race outerwall, said shoulder having an outer diameter in the radial directionsufficient to provide rigid axial support for said turbine cartridgeassembly upon one of said end walls of said housing.
 7. The dentalhandpiece of claim 1 wherein said flexible axial support meanscomprisesa flange connected to said outer race of said second bearingassembly, said flange extending radially outwardly from said outer race,and a resilient spacer member interposed between said flange on saidsecond bearing assembly outer race and a portion of said housing endwall adjacent said second bearing assembly, said spacer member havingspring-like resilience adapted to transmit a controlled compressionforce between said second bearing assembly outer race and said housingend wall.
 8. The dental handpiece of claim 7 wherein said resilientspacer member is a ring-like spring washer.
 9. The dental handpiece ofclaim 8 wherein said ring-like spring washer has a spring constantsufficient to provide a pre-load to each of said bearing assemblies inthe range of about 0.5 to about 1.5 pounds when said turbine cartridgeassembly is operably positioned within said housing.
 10. The dentalhandpiece of claim 1 wherein each of said first and second retainingmeans comprises:an outer wall on each of said bearing assembly outerraces, each of said outer walls facing radially outwardly of the axis ofsaid rotor shaft; a groove running circumferentially about each of saidouter race outer walls, each of said grooves lying in a planesubstantially perpendicular to the axis of said rotor shaft; aspring-like snap ring retained within each of said groove by the springbias of each of said snap rings, each of said snap rings forming anannular-shaped collar extending radially outwardly of each of said outerrace outer walls, each of said collars having an outer diameter in theradial direction sufficient to retard movement of said radial supportmeans or said flexible support means, or both, in an axial directionaway from said rotor shaft vanes.
 11. The dental handpiece of claim 1further including a bore within said rotor shaft, said bore having anaxis substantially coincident with the axis of said rotor shaft, saidrotor shaft having a threaded portion along a wall portion of said bore,and a collet having adjustable jaws for gripping a work tool, saidcollet having a threaded portion on an outer wall portion thereof forthreadably engaging said threaded portion of said rotor shaft.
 12. Aturbine cartridge assembly removably positionable within a housing of agas-driven motor of a dental handpiece wherein the housing is defined bya substantially cylindrical side wall and by a pair of oppositelydisposed end walls transverse to said side wall, and includes turbinecartridge assembly support means located on portions of the end walls ofthe housing; said turbine cartridge assembly comprising:a rotor shafthaving a plurality of vanes thereon, said rotor shaft defining an axisof rotation; a first bearing assembly comprising an inner race fixed tosaid rotor shaft, an outer race, and a plurality of movable bearingelements frictionally engaged with and confined between said inner raceand said outer race; a second bearing assembly comprising an inner racefixed to said rotor shaft, an outer race, and a plurality of movablebearing elements frictionally engaged with and confined between saidinner race and said outer race of said second bearing assembly; radialsupport means associated with each of said first and second bearingassemblies, said radial support means providing radial support for saidturbine cartridge assembly when in contact with the substantiallycylindrical side wall of the housing, when said turbine cartridgeassembly is operatively positioned within the housing of the handpiece;means for yieldingly coacting with the turbine cartridge assemblysupport means of the housing of the handpiece for axially pre-loadingsaid first and said second bearing assemblies when said turbinecartridge assembly is operably positioned within the housing, said meansfor yieldingly coacting with said turbine cartridge support meanscomprising a ring-like spring washer retained about the outer race of atleast one of said first and second bearing assemblies, said springwasher having a spring constant sufficient to provide a static pre-loadto said bearing assemblies in the range of about 0.5 to about 1.5pounds, when said turbine cartridge assembly is operably positionedwithin a handpiece housing with the spring washer interposed betweensaid bearing assembly outer race and the turbine cartridge support meansof the housing, said turbine cartridge assembly being adapted forplacement in, and removal from, the housing as a unitary assembly. 13.The turbine cartridge assembly of claim 12 wherein said radial supportmeans comprisesan outer wall on each of said bearing assembly outerraces, each of said outer walls facing radially outwardly of the axis ofsaid rotor shaft; and a ring of resilient material frictionally engagedabout a circumferential portion of each of said outer race outer wallsof each of said bearing assemblies, each of said rings having an outerdiameter sufficient to provide a compression fit between each of saidouter race outer walls and an adjacent portion of a handpiece housingside wall when said turbine cartridge assembly is operably positionedwithin the housing.
 14. The turbine cartridge assembly of claim 13wherein said ring of resilient material is an O-ring fabricated of amaterial selected from the group consisting of neoprene elastomer,fluorocarbon elastomer, ethylenepropylene elastomer andbutadiene/acrylonitrile elastomer.
 15. The turbine cartridge assembly ofclaim 12 further including rigid axial support means comprising a flangeconnected to said outer race of said first bearing assembly, said flangehaving an outer diameter in the radial direction sufficient to provideaxial support for said turbine cartridge assembly upon a portion of ahandpiece housing end wall when said turbine cartridge assembly isremovably positioned within a handpiece housing.
 16. The turbinecartridge assembly of claim 12 further including rigid axial supportmeans comprising:a flange connected to said outer race of said firstbearing assembly, said flange extending radially outwardly from saidouter race; and a substantially flat washer between said flange of saidfirst bearing assembly outer race and said radial support means, saidflat washer having an inner diameter smaller that the outer diameter ofsaid radially extending flange, and having an outer diameter ofsufficient dimension so that said flat washer supports said outer raceupon turbine cartridge assembly support means of a handpiece housingwhen said turbine cartridge assembly is operably positioned within thehousing.
 17. The turbine cartridge assembly of claim 12 furtherincluding rigid axial support means comprising:an outer wall on each ofsaid bearing assembly outer races, each of said outer walls facingradially outwardly of the axis of said rotor shaft; a groove runningcircumferentially about each of said outer race outer walls, each ofsaid grooves lying in a plane substantially perpendicular to the axis ofsaid rotor shaft; a spring-like snap ring retained within each of saidgrooves, each of said snap rings forming a shoulder extending radiallyoutwardly of each of said outer race outer walls, each of said shouldershaving an outer diameter in the radial direction sufficient to provideaxial support for said turbine cartridge assembly upon an adjacent endwall of a handpiece housing.
 18. A turbine cartridge assembly removablypositionable within a housing of a gas-driven motor of a dentalhandpiece wherein the housing is defined by a substantially cylindricalside wall and by a pair of oppositely disposed end walls transverse tosaid wall, and includes turbine cartridge assembly support means locatedon portions of said end walls of said housing; said turbine cartridgeassembly comprising:a rotor shaft having a plurality of vanes thereon,said rotor shaft defining an axis of rotation; a first bearing assemblycomprising an inner race fixed to said rotor shaft, an outer race, and aplurality of movable bearing elements frictionally engaged with andconfined between said inner race and said outer race; a second bearingassembly comprising an inner race fixed to said rotor shaft, an outerrace, and a plurality of movable bearing elements frictionally engagedwith and confined between said inner race and said outer race of saidsecond bearing assembly; radial support means associated with each ofsaid first and second bearing assemblies, said radial support meansproviding radial support for said turbine cartridge assembly when incontact with the substantially cylindrical side wall of a handpiecehousing; bearing pre-load means associated with at least one of saidbearing assembly outer races for yieldingly coacting with the turbinecartridge assembly support means in the housing of the handpiece foraxially pre-loading said first and said second bearing assemblies whensaid turbine cartridge assembly is operably positioned within thehousing, said turbine cartridge assembly being adapted for placement in,and removal from, the housing as a unitary assembly; retaining meansmounted on each of said bearing assembly outer races for preventingmovement of said radial support means or said means for yieldinglycoacting with the housing turbine cartridge assembly support means orboth in an axial direction away from said rotor shaft vanes.
 19. Theturbine cartridge assembly of claim 18 wherein said radial support meanscomprisesan outer wall on each of said bearing assembly outer races,each of said outer walls facing radially outwardly of the axis of saidrotor shaft; and a ring of resilient material frictionally engaged abouta circumferential portion of each of said outer race walls of each ofsaid first and second bearing assemblies, each of said rings having anouter diameter sufficient to provide a compression fit between each ofsaid outer race outer walls and an adjacent portion of a handpiecehousing side wall when said turbine cartridge assembly is operablypositioned within the housing.
 20. The turbine cartridge assembly ofclaim 19 wherein said ring of resilient material is an O-ring fabricatedof a material selected from the group consisting of neoprene elastomer,fluorocarbon elastomer, ethylenepropylene elastomer andbutadiene/acrylonitrile elastomer.
 21. The turbine cartridge assembly ofclaim 18 further including rigid axial support means comprising a flangeconnected to said outer race of said first bearing assembly, said flangehaving an outer diameter in the radial direction sufficient to provideaxial support for said turbine cartridge assembly upon a portion of ahandpiece housing end wall when said turbine cartridge assembly isremovably positioned within a handpiece housing.
 22. The turbinecartridge assembly of claim 18 further including a rigid axial supportmeans comprising:a flange connected to said outer race of said firstbearing assembly, said flange extending radially outwardly from saidouter race; and a substantially flat washer between said flange on saidfirst bearing assembly outer race and said radial support means, saidflat washer having an inner diameter smaller that the outer diameter ofsaid radially extending flange, and having an outer diameter ofsufficient dimension so that said flat washer supports said outer raceupon turbine cartridge assembly support means of a handpiece housingwhen said turbine cartridge assembly is operably positioned within thehousing.
 23. The turbine cartridge assembly of claim 18 furtherincluding rigid axial support means comprising:an outer wall on each ofsaid first and second bearing assembly outer races, each of said outerwalls facing radially outwardly of the axis of said rotor shaft; agroove running circumferentially about each of said outer race outerwalls, each of said grooves lying in a plane substantially perpendicularto the axis of said rotor shaft; a spring-like snap ring retained withineach of said grooves, each of said snap rings forming a shoulderextending radially outwardly of each of said outer race outer walls,each of shoulders having an outer diameter in the radial directionsufficient to provide axial support for said turbine cartridge assemblyupon an adjacent end wall of a handpiece housing when said turbinecartridge assembly is operably positioned within the housing.
 24. Theturbine cartridge assembly of claim 18 wherein said means for yieldinglycoacting with turbine cartridge support means of a handpiece housingcomprises a resilient spacer member retained about said outer race of atleast one of said first and second bearing assemblies, said spacermember adapted to transmit a controlled compression force between saidouter race and the turbine cartridge assembly support means of thehousing, so as to urge said outer race in a axial direction, toward saidrotor vanes.
 25. The turbine cartridge assembly of claim 24 wherein saidresilient spacer member is a ring-like spring washer.
 26. The turbinecartridge assembly of claim 25 wherein said ring-like spring washer hasa spring constant sufficient to provide a static pre-load to saidbearing assemblies in the range of about 0.5 to about 1.5 pounds, whensaid turbine cartridge assembly is operably positioned within ahandpiece housing with the spring washer interposed between said bearingassembly outer race and turbine cartridge support means of the housing.27. The turbine cartridge assembly of claim 18 wherein said means foryieldingly coacting with turbine cartridge support means of a handpiecehousing comprises:a first resilient spacer and member retained aboutsaid outer race of said first bearing assembly, said first spacer memberadapted to transmit a controlled compression force between said outerrace of said first bearing assembly and an adjacent portion of theturbine cartridge assembly support means of the housing; a secondresilient spacer member retained about said outer race of said secondbearing assembly said second spacer member adapted to transmit acontrolled compression force between said outer race of said secondbearing assembly and an adjacent portion of the turbine cartridgeassembly support means of the housing; wherein said first and secondspacer members cooperate with the turbine cartridge support means of thehousing to provide axial pre-loading of said first and second bearingassemblies.
 28. The turbine cartridge assembly of claim 27 wherein eachof said resilient spacer member is a ring-like spring washer.
 29. Theturbine cartridge assembly of claim 28 wherein said ring-like springwashers have spring constants sufficient to provide a static pre-load tosaid bearing assemblies in the range of about 0.5 to about 1.5 pounds,when said turbine cartridge assembly is operably positioned within ahandpiece housing with said spring washer interposed between saidbearing assembly outer races and the turbine cartridge support means ofthe housing.
 30. The turbine cartridge assembly of claim 18 wherein saidretaining means comprises:an outer wall on each of said first and secondbearing assembly outer races, each of said outer walls facing radiallyoutwardly of the axis of said rotor shaft; a groove runningcircumferentially about each of said outer race outer walls, each ofsaid grooves lying in a plane substantially perpendicular to the axis ofsaid rotor shaft; a spring-like snap ring retained within each of saidgrooves by the spring bias of each of said snap rings, each of said snaprings forming an annular-shaped collar extending radially outwardly ofeach of said outer race outer walls, each of said collars having anouter diameter in the radial direction sufficient to retard movement ofsaid radial support means and said flexible support means in an axialdirection away from said rotor shaft vanes.
 31. A dental handpiececomprising a gas-driven motor, said motor including a housing and aturbine cartridge assembly within said housing, said housing defined bya substantially cylindrical side wall and by a pair of oppositelydisposed end walls transverse to said side wall, said housing havingturbine cartridge assembly support means located on portions of said endwalls for supporting said turbine cartridge assembly, said turbinecartridge assembly removably positionable as a unitary assembly withinsaid housing, said turbine cartridge assembly comprising:a rotor shafthaving a plurality of vanes thereon, said rotor shaft having an axis ofrotation substantially coincident with the axis of said substantiallycylindrical side wall of said housing; a first bearing assemblycomprising an inner race fixed to said rotor shaft, an outer race, and aplurality of movable bearing elements frictionally engaged with andconfined between said inner race and said outer race; a second bearingassembly comprising an inner race fixed to said rotor shaft, an outerrace, and a plurality of movable bearing elements frictionally engagedwith and confined between said inner race and said outer race of saidsecond bearing assembly; radial support means associated with each ofsaid first and second bearing assemblies, said radial support meanscomprising a resilient member interposed between each of said bearingassemblies and an adjacent portion of said housing side wall forproviding radial support for said turbine cartridge assembly when incontact with said substantially cylindrical side wall of said housing;rigid axial support means connected to each of said outer races of saidfirst and second bearing assemblies for axially supporting said outerraces upon said turbine cartridge support means of said housing; andretaining means associated with each of said bearing assembly outerraces for retaining said radial support means upon said turbinecartridge assembly and preventing movement of said radial support meansin an axial direction away from said rotor shaft vanes during removal,or insertion, of said turbine cartridge assembly from, or in, said motorhousing.
 32. The dental handpiece of claim 31 wherein said radialsupport means comprisesan outer wall on each of said first and secondbearing assembly outer races, each of said outer walls facing radiallyoutwardly of the axis of said rotor shaft; and each of said resilientmembers comprise a ring of resilient material frictionally engaged abouta circumferential portion of each of said outer race outer walls of eachof said first and second bearing assemblies, each of said rings havingan outer diameter sufficient to provide a compression fit between eachof said outer race outer walls and an adjacent portion of said housingside wall when said turbine cartridge assembly is operably positionedwithin said housing.
 33. The dental handpiece of claim 32 wherein saidring of resilient material is an O-ring fabricated of a materialselected from the group consisting of neoprene elastomer, fluorocarbonelastomer, ethylenepropylene elastomer and butadiene/acrylonitrileelastomer.
 34. The dental handpiece of claim 31 wherein said rigid axialsupport means comprises a flange connected to each of said outer racesof said first and second bearing assemblies, each of said flanges havingan outer diameter in the radial direction sufficient to provide axialsupport for said turbine cartridge assembly upon a portion of saidhousing end wall.
 35. The dental handpiece of claim 31 wherein saidrigid axial support means comprises:a flange connected to each of saidouter races of said first and second bearing assemblies, each of saidflanges extending radially outwardly from each of said outer races; anda substantially flat washer interposed between each of said flanges oneach of said bearing assembly outer races and an adjacent portion ofsaid turbine cartridge support means of said housing, each of said flatwashers having an inner diameter smaller than the outer diameter of saidradially extending flange adjacent to said washer, and having an outerdiameter of sufficient dimension so that said flat washers support eachof said outer races upon turbine cartridge assembly support meanslocated on wall portions of the housing.
 36. The dental handpiece ofclaim 31 wherein said rigid axial support means comprisesan outer wallon each of said bearing assembly outer races, each of said outer wallsfacing radially outwardly of the axis of said rotor shaft; a grooverunning circumferentially about each of said outer race outer walls,each of said grooves lying in a plane substantially perpendicular to theaxis of said rotor shaft; a spring-like snap ring retained within eachof said grooves, each of said snap rings forming a shoulder extendingradially outwardly of each of said outer race outer walls, each of saidshoulder having an outer diameter in the radial direction sufficient toprovide axial support for said turbine cartridge assembly upon one ofsaid end walls of said housing.
 37. The dental handpiece of claim 31wherein each of said retaining means comprises:an outer wall of each ofsaid bearing assembly outer races, each of said outer walls facingradially outwardly of the axis of said rotor shaft; a groove runningcircumferentially about each of said outer race outer walls, each ofsaid grooves lying in a plane substantially perpendicular to the axis ofsaid rotor shaft; a spring-like snap ring retained within each of saidgrooves by the spring bias of each of said snap rings, each of said snapring forming an annular-shaped collar extending radially outwardly ofeach of said outer race outer walls, each of said collars having anouter diameter in the radial direction sufficient to retard movement ofsaid radial support means or said flexible support means, or both, in anaxial direction away from said rotor shaft vanes.
 38. A turbinecartridge assembly removably positionable within a housing of agas-driven motor of a dental handpiece wherein the housing is defined bya substantially cylindrical side wall and by a pair of oppositelydisposed end walls transverse to said wall, and includes turbinecartridge assembly support means located on portions of said end wallsof said housing; said turbine cartridge assembly comprising:a rotorshaft having a plurality of vanes thereon, said rotor shaft defining anaxis of rotation; a first bearing assembly comprising an inner racefixed to said rotor shaft, an outer race, and a plurality of movablebearing elements frictionally engaged with and confined between saidinner race and said outer race; a second bearing assembly comprising aninner race fixed to said rotor shaft, an outer race, and a plurality ofmovable bearing elements frictionally engaged with and confined betweensaid inner race and said outer race of said second bearing assembly;radial support means associated with each of said first and secondbearing assemblies, said radial support means providing radial supportfor said turbine cartridge assembly when in contact with thesubstantially cylindrical side wall of a handpiece housing; retainingmeans mounted on each of said bearing assembly outer races forpreventing movement of said radial support means in an axial directionaway from said rotor shaft vanes during removal, or insertion, of saidturbine cartridge assembly from, or in, said motor housing.
 39. Theturbine cartridge assembly of claim 38 wherein said radial support meanscomprisesan outer wall on each of said bearing assembly outer races,each of said outer walls facing radially outwardly of the axis of saidrotor shaft; and a ring of resilient material frictionally engaged abouta circumferential portion of each of said outer race outer walls of eachof said first and second bearing assemblies, each of said rings havingan outer diameter sufficient to provide a compression fit between eachof said outer race outer walls and an adjacent portion of a handpiecehousing side wall when said turbine cartridge assembly is operablypositioned within the housing.
 40. The turbine cartridge assembly ofclaim 39 wherein said ring of resilient material is an O-ring fabricatedof a material selected from the group consisting of neoprene elastomer,fluorocarbon elastomer, ethylenepropylene elastomer andbutadiene/acrylonitrile elastomer.
 41. The turbine cartridge assembly ofclaim 38 further including rigid axial support means comprising a flangeconnected to each of said outer races of said first and second bearingassemblies, each of said flanges having an outer diameter in the radialdirection sufficient to provide axial support for said turbine cartridgeassembly upon portions of handpiece housing end walls when said turbinecartridge assembly is removably positioned within a handpiece housing.42. The turbine cartridge assembly of claim 38 further including rigidaxial support means comprising:a flange connected to each of said outerrace of said first and second bearing assemblies, each of said flangesextending radially outwardly from each of said outer races; and asubstantially flat washer between each of said flanges of said first andsecond bearing assembly outer races and said associated radial supportmeans, each of said flat washers having an inner diameter smaller thatthe outer diameter of said radially extending flange, and having anouter diameter of sufficient dimension so that each of said flat washerssupports said outer race adjacent said flat washer upon turbinecartridge assembly support means of a handpiece housing when saidturbine cartridge assembly is operably positioned within the housing.43. The turbine cartridge assembly of claim 38 further including rigidaxial support means comprising:an outer wall on each of said bearingassembly outer races, each of said outer wall facing radially outwardlyof the axis of said rotor shaft; a groove running circumferentiallyabout each of said outer race outer walls, each of said grooves lying ina plane substantially perpendicular to the axis of said rotor shaft; aspring-like snap ring retained within each of said groove by the springbias of each of said snap rings, each of said snap rings forming ashoulder extending radially outwardly of each of said outer race outerwalls, said shoulders having an outer diameter in the radial directionsufficient to provide axial support for said turbine cartridge assemblyupon an adjacent end wall of a handpiece housing.
 44. The turbinecartridge assembly of claim 38 wherein said retaining means comprises:anouter wall on each of said bearing assembly outer races, each of saidouter walls facing radially outwardly of the axis of said rotor shaft; agroove running circumferentially about each of said outer race outerwalls, each of said grooves lying in a plane substantially perpendicularto the axis of said rotor shaft; a spring-like snap ring retained withineach of said grooves by the spring bias of each of said snap rings, eachof said snap rings forming an annular-shaped collar extending radiallyoutwardly of each of said outer race outer walls, each of said collarshaving an outer diameter in the radial direction sufficient to retainsaid radial support means upon said turbine cartridge assembly.
 45. Adental handpiece comprising a gas-driven motor, said motor including ahousing and a turbine cartridge assembly within said housing, saidhousing defined by a substantially cylindrical side wall and by a pairof oppositely disposed end walls transverse to said side wall, saidhousing having turbine cartridge assembly support means located onportions of said end walls for supporting said turbine cartridgeassembly, said turbine cartridge assembly removably positionable as aunitary assembly within said housing, said turbine cartridge assemblycomprising:a rotor shaft having a plurality of vanes thereon, said rotorshaft having an axis of rotation substantially coincident with the axisof said substantially cylindrical side wall of said housing; a firstbearing assembly comprising an inner race fixed to said rotor shaft, anouter race having an outer wall facing radially outwardly of the axis ofsaid rotor shaft, and a plurality of movable bearing elementsfrictionally engaged with and confined between said inner race and saidouter race; a second bearing assembly comprising an inner race fixed tosaid rotor shaft, an outer race having an outer wall facing radiallyoutwardly of the axis of said rotor shaft, and a plurality of movablebearing elements frictionally engaged with and confined between saidinner race and said outer race of said second bearing assembly; a flangeconnected to each of said outer race outer walls, said flange extendingradially outwardly from said outer race; a substantially flat washerinterposed between said flange on said first bearing assembly outer raceand said turbine cartridge support means of said housing, said flatwasher having an inner diameter smaller than the outer diameter of saidradially extending flange, and having an outer diameter of sufficientdimension so that said flat washer supports said outer race upon saidturbine cartridge assembly support means of said housing; a ring ofresilient material frictionally engaged about a circumferential portionof said outer race outer wall of each of said bearing assemblies toprovide radial support for said turbine cartridge assembly upon saidmotor housing side wall, said ring having an outer diameter sufficientto provide a compression fit between said outer race outer wall and aportion of said housing side wall; a groove running circumferentiallyabout said outer race outer wall of each of said bearing assemblies,said groove lying in a plane substantially perpendicular to the axis ofsaid rotor shaft; a spring-like snap ring retained within each of saidgrooves by the spring bias of said snap ring, said snap ring forming anannular-shaped collar extending radially outwardly of said outer raceouter wall, each of said collars having an outer diameter in the radialdirection sufficient to retain said flat washer and said ring ofresilient material upon each of said turbine cartridge assembly outerrace outer walls in cooperation, respectively, with said flange of eachof said bearing assembly outer race outer walls; and a resilient spacerring interposed between said flange and said flat washer of said secondbearing assembly outer race, said spacer ring having a spring-likeresilience adapted to transmit a controlled compression force betweensaid outer race and a portion of said housing end wall adjacent saidsecond bearing assembly so as to provide axial pre-loading of said firstand second bearing assemblies within said motor housing.
 46. The dentalhandpiece of claim 45 wherein said ring of resilient materials is anO-ring fabricated of a material selected from the group consisting ofneoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomerand butadiene/acrylonitrile elastomer.
 47. The dental handpiece of claim45 wherein said resilient spacer ring is a spring washer.
 48. The dentalhandpiece of claim 47 wherein said spring washer has a spring constantsufficient to provide a static pre-load to said bearing assemblies inthe range of about 0.5 to about 1.5 pounds, when said turbine cartridgeassembly is operably positioned within said housing.
 49. The dentalhandpiece of claim 45 further comprising a resilient spacer ringinterposed between said flange and said flat washer of said firstbearing assembly outer race, said spacer ring having a spring-likeresilience adapted to transmit a controlled compression force betweensaid first bearing assembly outer race and a portion of said housing endwall adjacent said first bearing assembly so as to provide axialpre-loading of said first and second bearing assemblies within saidmotor housing in cooperation with said resilient spacer ring of saidsecond bearing assembly.
 50. The dental handpiece of claim 49 whereineach of said spacer rings of said first and second bearing assemblies isa spring washer.
 51. The dental handpiece of claim 50 wherein saidspring washers have spring constants sufficient to provide staticpre-loading to said first and second bearing assemblies in the range ofabout 0.5 to about 1.5 pounds, when said turbine cartridge assembly isoperably positioned within said housing.
 52. A dental handpiececomprising a gas-driven motor, said motor including a housing and aturbine cartridge assembly within said housing, said housing defined bya substantially cylindrical side wall and by a pair of oppositelydisposed end walls transverse to said side wall, said housing havingturbine cartridge assembly support means located on portions of saidwalls for supporting said turbine cartridge assembly, said turbinecartridge assembly removably positionable as a unitary assembly withinsaid housing, said turbine cartridge assembly comprising:a rotor shafthaving a plurality of vanes thereon, said rotor shaft having an axis ofrotation substantially coincident with the axis of said substantiallycylindrical side wall of said housing; a first bearing assemblycomprising an inner race fixed to said rotor shaft, an outer race, and aplurality of movable bearing elements frictionally engaged with andconfined between said inner race and said outer race; a second bearingassembly comprising an inner race fixed to said rotor shaft, an outerrace, and a plurality of movable bearing elements frictionally engagedwith and confined between said inner race and said outer race of saidsecond bearing assembly; radial support means associated with each ofsaid first and second bearing assemblies, said radial support meansproviding radial support for said turbine cartridge assembly upon saidsubstantially cylindrical side wall of said housing; bearing pre-loadmeans comprising flexible axial support means associated with each ofsaid outer races of said first and second bearing assemblies foryieldingly supporting said outer races upon said turbine cartridgesupport means of said housing; first retaining means for retaining saidradial support means and said flexible axial support means upon saidouter race of said first bearing assembly, said first retaining meanspreventing movement of said radial support means in an axial directionaway from said rotor shaft vanes; and second retaining means forretaining said radial support means and said flexible axial supportmeans upon said outer race of said second bearing assembly, said secondretaining means preventing movement of said radial support means andsaid flexible support means in an axial direction away from said rotorshaft vanes; whereby said flexible axial support means coact withturbine cartridge support means of said housing to provide axialpre-loading of said first and second bearing assemblies when saidturbine cartridge assembly is operatively positioned within saidhousing. .Iadd.
 53. A self-contained cartridge assembly free of anyouter enclosure for insertion and use as a unit in and for removal froma plurality of dental handpieces in which the housing interiors aredifferent in size and in which each housing has a fluid inlet to directfluid into the housing and an outlet to exhaust fluid from the housingand in which the housing becomes the enclosure for said cartridgeassembly when said cartridge assembly is positioned therein, saidcartridge assembly comprising sleeve shaped means of substantially thelength of the housing and for engagement with a dental tool, a turbinehaving impeller faces extending into the housing and for impingementthereagainst by fluid directed into the housing through the fluid inletthereof to rotate said turbine, said impeller being connected with saidsleeve for conjoint rotation therewith, rollable bearings fixed on saidsleeve on opposite sides of said impeller, and engaging means capturedon said rollable bearings extending outward therefrom for fluid tightengagement with the wall of the handpiece housing on opposite ends ofsaid impeller to confine and direct the inlet fluid against saidimpeller and the faces thereof to contain the fluid from flowing outwardfrom between said cartridge and the engagement of said engaging meanswith the housing. .Iaddend. .Iadd.54. In a cartridge type turbineassembly as in claim 53, said engaging means being yieldable to cushionthe engagement between said cartridge type turbine assembly and thehousing to absorb vibrations therebetween. .Iaddend. .Iadd.55. In acartridge type turbine assembly as in claim 54, said engaging meansbeing of a size and being deformable to engage fluid tightly withhousing walls of different sizes. .Iaddend. .Iadd.56. In a cartridgetype turbine assembly as in claim 55, seat means on said rollablebearings mounting said engaging means to support the same in fixedposition thereon and to prevent removal of said engaging means fromtheir respective bearing. .Iaddend. .Iadd.57. In a cartridge typeturbine assembly as in claim 55, said rollable bearings being spacedfrom and on opposite sides of said impeller faces from between 0.030inches to 0.060 inches, and said impeller faces being spaced from thewall of the housing from between 0.010 inches and 0.030 inches..Iaddend. .Iadd.58. In a cartridge type turbine assembly as in claim 53,said rollable bearings being spaced from and on opposite sides of saidimpeller faces from between 0.030 inches to 0.060 inches. .Iaddend..Iadd.59. In a cartridge type turbine assembly as in claim 53, saidimpeller faces being spaced from the wall of the housing from between0.010 inches and 0.030 inches. .Iaddend. .Iadd.60. In combination with aturbine operated dental handpiece having a housing with an interior wallto accommodate a turbine and fluid inlet and outlet means for the supplyand exhaust respectively of fluid from the housing, a unitary turbineassembly free of any enclosure comprising rollable bearings relativelyspaced from each other and each said bearing having inner and outerraces, a rotatable turbine in said space between said bearings andhaving a plurality of impeller faces to receive the impingement of fluidthereagainst in the housing, seal means captured on the outer races ofsaid bearings in fluid tight direct engagement with the interior wall ofthe housing to enclose said turbine between said spaced bearings and theinterior wall such that fluid entering the housing is caused to impingeupon the impeller faces and to exhaust outward from the housing throughthe fluid outlet means, and an elongated dental tool holder mountingsaid bearings in their spaced relationship and with said turbinetherebetween, said tool holder including a sleeve connected with saidinner races of said bearings and with said turbine to rotate conjointlytherewith, and said seal means being releasably engageable with theinterior wall of the housing to enable said unitary turbine assembly tobe inserted into and removed from engagement as a unit with the housingwall so that the housing becomes the enclosure for the unitary turbineassembly. .Iaddend. .Iadd.61. A unitary turbine assembly as in claim 60,said seal means being of a yieldable material and engaging with theinterior walls of different sizes of housings fluid tightly to cause theouter race of its respective bearing to be non-rotatable relative tosuch engaged wall. .Iaddend. .Iadd.62. A unitary turbine assembly as inclaim 60, said bearings being spaced from and on opposite sides of saidrotatable turbine from between 0.030 inches to 0.060 inches. .Iaddend..Iadd.63. A unitary turbine assembly as in claim 60, said impeller facesbeing spaced from the wall of the housing of the dental handpiece frombetween 0.010 inches to 0.030 inches. .Iaddend. .Iadd.64. A unitaryturbine assembly as in claim 60, a recessed seat defined in theperiphery of each of the outer races of said bearings, and said sealmeans on each of the outer races of said bearings being mounted within arespective one of said peripheral seats to retain the seal means fixedwith respect to its respective bearing until forcefully removedtherefrom for replacement. .Iaddend. .Iadd.65. A wall-less unitarycartridge type turbine assembly free of an outer enclosure for use in acircular housing of a dental handpiece in which the interior circularwall of the housing is utilized as the wall of the turbine assembly,said assembly comprising a rotatable axially elongated chuck havingoperable means for releasable engagement with a dental tool, a sleeveconnected with said chuck for rotation therewith and rotation relativethereto to actuate with said operable means to releasably engage adental tool, a turbine on said sleeve intermediate the ends thereof forrotation therewith, said turbine having a plurality of circumferentiallyspaced impeller faces against which fluid may impinge to rotate saidturbine, rollable bearings spaced axially along said sleeve and onopposite sides of said impeller and axially from said impeller faces,each of said rollable bearings having inner and outer races with saidinner race connected with said sleeve for rotation therewith and saidouter race being rotatable with respect thereto, and seal means ofyieldable deformable material mounted on said outer race of each of saidbearings and from displacement therefrom so that said chuck, sleeve,turbine, rollable bearings and seal means are connected together as aunit free of an enclosing wall and for use as a cartridge type insertinto and for removal from the housings of different dental handpieceswith said seal means yielding to fit into the interior wall of thehousing and deforming into fluid-tight engagement therewith such thatthe housing wall becomes the temporary enclosing wall of said turbineassembly while the same is therein and until said turbine assembly isremoved from said housing by disengagement of said seal means therefrom..Iaddend. .Iadd.66. A wall-less unitary cartridge type turbine assemblyas in claim 65, said outer races of each of said rollable bearingshaving a circumferential seat defined in the outer periphery thereof inwhich said seal means is mounted and prevented from displacement..Iaddend. .Iadd.67. A wall-less unitary cartridge type turbine assemblyas in claim 65, said rollable bearings being spaced on opposite axialsides of said impeller faces from between 0.030 inches and 0.060 inchesand said impeller faces being arranged on said unitary cartridge typeturbine assembly such that when the same is within the housing saidimpeller faces are spaced from the interior wall thereof from between0.010 inches and 0.030 inches. .Iaddend.